(92k b/w photo from "Red Stars in the Sky") V.A.Matsiyevich, Commander of the 26
GvIAP (Leningrad Air Defence Troops)
reading Stalin's order of the day to the regiment's staff in front of Spitfire L.F.Mk.IXE
fighters (note clipped wings and 20mm cannon in outboard position) in April
1945. The aircraft in the foreground
has the enlarged vertical tail of late production machines.

With
the arrival of the Fw 190A on the Channel coast late in
1941
the RAF faced a serious dilemma. The new German fighter
outclassed the Spitfire Mk.V on nearly every count, so
the need for an improved Spitfire variant became paramount. But it was also felt that
the introduction of a radically changed development would take too long and seriously
interrupt production and operations at a critical stage of the war. So an interim
solution had to be chosen, which was basically a more powerful
Mk.V and could be produced and delivered to
the squadrons with the least possible delay.

This interim type was designated Spitfire Mk.IX and consisted of a basic
Mk.V airframe married to a two-speed two-stage
supercharged Merlin 61 engine rated at 1,565hp which drove a four-blade Rotol propeller.
Apart from the changes necessary to install this engine no other changes were made to the basic
Spitfire V airframe. Externally the Spitfire IX
could be distinguished from its predecessor by its four-blade propeller, the six individual
exhaust stubs on each side, the symmetrical radiators under the wings and (late aircraft only)
the enlarged vertical fin. These differences normally could not be recognized at combat range
which provided Spitfire IX pilots with some tactical advantage at first, when their machines
were mistaken for the inferior Spitfire Vs by their adversaries.
The Mk.IX entered service with the RAF in July
1942.
Later in its service life this variant was employed primarily as a fighter-bomber, having been replaced
as an interceptor by Spitfire models with Rolls-Royce Griffon engines.

Depending on the particular version of the Merlin fitted, the Spitfire IX
was built in three sub-types:

The L.F.s frequently had clipped wings, which improved performance at low altitudes, but
apart from this feature the three sub-types were externally indistinguishable.

As with the Spitfire V the
wing/armament layout was denoted by a suffix letter to the designation. Besides the "B"
(only on a few early machines) and "C" wings already used on the
Mk.V the Spitfire IX introduced the so-called
"E" wing. This wing had the two 7.7mm machine
guns replaced by a single 12.7mm Browning gun. This gun was installed in what had
been the inner cannon bay of the "C" wing and the 20mm cannon was moved to the
outboard position. So the total of 5,665 Spitfire IXs delivered consisted of the following
sub-types (source: Profile Publications, No.206):

L.F.Mk.IXB, L.F.Mk.IXC, L.F.Mk.IXE

F.Mk.IXB, F.Mk.IXC, F.Mk.IXE

H.F.Mk.IXC, H.F.Mk.IXE

In later years some Spitfire IXs depending on their role received the designations F.B.Mk.IX (fighter-bomber), F.R.Mk.IX
(fighter-reconnaissance), T.T.Mk.IX (target towing) or MET.Mk.IX (meteorological). A further development of the Spitfire IX and
the last major production variant (1,054 built from
1944
onwards) with Merlin
engine was the Spitfire L.F.Mk.XVIC or E (with a Packard-built Merlin 266 of
1,705hp), a fighter-bomber which in its later versions had a cut-down rear fuselage and an all-round-vision cockpit canopy
(one source quotes that this modification was made on some late Spitfire IXs also). There was also built in
1943
one prototype (MJ892) of a floatplane version (with a top speed of
607km/h the fastest float seaplane of World War II) of the Spitfire IX, but further its development was abandoned early
in 1944.

(22k b/w from "War Planes of the Second World War - Fighters Vol.2") 3-view drawing of the Spitfire Mk.IXC.

To the Soviet Union were sent under the "Aid to Russia" program a
total of 1,188 Spitfire Mk.IXs, all but two of them being L.F.Mk.IXs.
These machines were delivered between mid-
1944 and April
1945.
There is no information available about possible losses en route. Details
about the service career of these aircraft with the Soviets are also lacking. But there is pictorial evidence (see below), that
the Russians converted some of those machines into two-seat conversion trainers (an equivalent modification also appeared
in England in small numbers after the war).